twogirls,I posted the technique on getting rid of the nudibranches.There are no quick fixes.I've research and research,there doesn't seem to be any predators that feed on them.Remove the zoos and freshwater dip them,put them back in the DT or QT.If you put them in the DT as bait then you need to do a freshwater dip every few days.If you put the zoos in QT,the remaining nudibranches die pretty quickly,around a week without there source of food.
ps...If you freshwater dip in a separate container(1gal.)then you have to set the temp and PH to your display tank.I'm sorry this is what you have to do to save your zoos.